The present invention relates to a heating boiler or furnace for burning oil or gas.
Normally, furnaces, especially those that are provided with burners for burning fuel oil, are embodied and operated in such a way that, while utilizing the heating value (lower heating value) of the fuel to the greatest extent, the flue gases leave the furnace at a temperature of 150.degree. C. or greater, so that a sufficient draft is produced in the chimney, and no flue tar or other residue results in the chimney due to condensation of the water vapor content of the flue gases. However, by utilizing the fuel value (upper heating value) of the fuel, endeavors have been made to still further increase the furnace efficiency by utilizing and lowering the temperature of the flue gases, before they leave the furnace or enter the chimney, to such an extent with so-called combustion or fuel value furnaces that the temperature falls below the dew point of the flue gas moisture, and a condensation of the water vapor portion in the flue gases, which condensation releases the heat of vaporization of the water, takes place.
It is an object of the present invention to provide a furnace that is suitable and can be utilized as a fuel value furnace for flue gas condensation operation, but that, by a simple conversion, can also be operated as a furnace for conventional operation without the formation of condensate and at normal flue gas temperatures of about 150.degree. to 200.degree. C. where the chimney conditions do not permit a lower temperature of the flue gases as they leave the furnace.